1. Field of the Invention
The present invention relates generally to mobile communication devices which provide for both voice and data call capabilities, and more particularly to the prioritization of voice call requests during data communication sessions with the mobile device.
2. Description of the Related Art
A mobile communication device, such as a mobile station operating in a wireless communication network, may provide for both voice and data communications for an end user. The mobile device may, for example, be compatible with 3rd Generation (3G) communication standards. Some versions of 3G standards (such as IS-2000 Release 0), however, do not allow for the simultaneous communication of both voice and user data at the mobile device. Such a mobile device is capable of maintaining either a voice call or a data call, but not a voice call and a data call at the same time.
An Internet Protocol (IP) connection may be utilized to communicate packet data to and from the mobile device. To provide packet data connectivity between the mobile device and an IS-2000-compliant network, a Point-to-Point Protocol (PPP) link layer connection is also established between the mobile device and the network. A packet data service is said to be in an “active” state while the PPP connection is established. An “always-on, always-connected” mobile device is supposed to maintain PPP connectivity all of the time and maintain this active state. When the PPP connectivity is terminated, the packet data service is said to be in an “inactive” state.
An active packet data service may be in either a “connected” state or a “dormant” state. A packet data service is said to be “connected” when a traffic channel for a data call is established between the mobile device and the network. In this connected state, data is actively exchanged between the mobile device and the network over the traffic channel or is expected. If no user data is received or transmitted within a predetermined time period (e.g. 10 or 20 seconds), the traffic channel is torn down either by the mobile device or the network. Here, the packet data service is said to enter into the “dormant” state. In the dormant state, the IP connection and the PPP session are still maintained but the physical layer and radio resources are released. If data communications are subsequently resumed, the packet data service will again become “connected” where the traffic channel is reestablished for communicating data.
Traditionally, the operation of this type of mobile device is limited in that the end user cannot initiate a voice call from the mobile device during a data call (i.e. when the packet data service is in the connected state). The mobile device permits the end user to place a voice call only if the packet data service is in the inactive state or the dormant state. If otherwise attempted, the mobile device will not initiate voice call processing. In some cases, the end user is not even aware of the data communication activity and is not alerted to the reason why the voice call could not be placed. A wireless network similarly cannot successfully initiate a voice call to the mobile device when the mobile device is engaged in a data call. If a voice call is attempted to a mobile device which is already engaged in a data call, the network typically provides a busy signal to the caller or sends the call to voicemail of the mobile device. Unfortunately, the user ordinarily has to wait until the expiration of inactivity time (e.g. 10 or 20 seconds of no user data being received or transmitted) until the dormant state is entered in order to place or receive the voice call. As apparent, time-critical voice calls may be undesirably missed during less time-critical data communications.